PPP1R15A-mediated dephosphorylation of eIF2α is unaffected by Sephin1 or Guanabenz

  1. Ana Crespillo-Casado  Is a corresponding author
  2. Joseph E Chambers
  3. Peter M Fischer
  4. Stefan J Marciniak
  5. David Ron  Is a corresponding author
  1. University of Cambridge, United Kingdom
  2. University of Nottingham, United Kingdom

Abstract

Dephosphorylation of translation initiation factor 2 (eIF2α) terminates signalling in the mammalian integrated stress response (ISR) and has emerged as a promising target for modifying the course of protein misfolding diseases. The [(o-chlorobenzylidene)amino]guanidines (Guanabenz and Sephin1) have been proposed to exert protective effects against misfolding by interfering with eIF2α-P dephosphorylation through selective disruption of a PP1-PPP1R15A holophosphatase complex. Surprisingly, they proved inert in vitro affecting neither stability of the PP1-PPP1R15A complex nor substrate-specific dephosphorylation. Furthermore, eIF2α-P dephosphorylation, assessed by a kinase shut-off experiment, progressed normally in Sephin1-treated cells. Consistent with its role in defending proteostasis, Sephin1 attenuated the IRE1 branch of the endoplasmic reticulum unfolded protein response. However, repression was noted in both wildtype and Ppp1r15a deleted cells and in cells rendered ISR-deficient by CRISPR editing of the Eif2s1 locus to encode a non-phosphorylatable eIF2α (eIF2αS51A). These findings challenge the view that [(o-chlorobenzylidene)amino]guanidines restore proteostasis by interfering with eIF2α-P dephosphorylation.

Article and author information

Author details

  1. Ana Crespillo-Casado

    Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
    For correspondence
    ac880@cam.ac.uk
    Competing interests
    The authors declare that no competing interests exist.
  2. Joseph E Chambers

    Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0003-4675-0053
  3. Peter M Fischer

    Division of Biomolecular Science and Medicinal Chemistry, School of Pharmacy, University of Nottingham, Nottingham, United Kingdom
    Competing interests
    The authors declare that no competing interests exist.
  4. Stefan J Marciniak

    Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0001-8472-7183
  5. David Ron

    Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
    For correspondence
    dr360@medschl.cam.ac.uk
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-3014-5636

Funding

Wellcome (200848/Z/16/Z)

  • David Ron

Wellcome (100140)

  • David Ron

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Reviewing Editor

  1. Vivek Malhotra, The Barcelona Institute of Science and Technology, Spain

Version history

  1. Received: February 16, 2017
  2. Accepted: April 21, 2017
  3. Accepted Manuscript published: April 27, 2017 (version 1)
  4. Version of Record published: May 12, 2017 (version 2)

Copyright

© 2017, Crespillo-Casado et al.

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.

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  1. Ana Crespillo-Casado
  2. Joseph E Chambers
  3. Peter M Fischer
  4. Stefan J Marciniak
  5. David Ron
(2017)
PPP1R15A-mediated dephosphorylation of eIF2α is unaffected by Sephin1 or Guanabenz
eLife 6:e26109.
https://doi.org/10.7554/eLife.26109

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https://doi.org/10.7554/eLife.26109

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